Blowout preventer with a threaded ram

Abstract

An assembly for a blowout preventer includes a ram having a threaded opening. The assembly also includes a threaded shaft to engage the threaded opening and a motor to drive rotation of the threaded shaft. Rotation of the threaded shaft causes the ram to move axially along the threaded shaft.

The invention claimed is: 
     
       1. An assembly for a blowout preventer, comprising:
 a ram comprising a threaded opening and defining an alignment interface including an alignment slot configured to receive a protrusion extending from a housing of the blowout preventer; 
 a threaded shaft configured to engage the threaded opening; and 
 a motor configured to drive rotation of the threaded shaft, wherein rotation of the threaded shaft causes the ram to move axially along the threaded shaft, 
 wherein the alignment interface including the alignment slot is defined by a lower surface of the ram opposite a top packer segment that is configured to create a seal against the housing of the blowout preventer, and 
 wherein the alignment interface is provided at a location that does not interfere with the seal between the top packer segment and the housing of the blowout preventer. 
 
     
     
       2. The assembly of  claim 1 , wherein the ram comprises a pipe ram and comprises a packer assembly configured to seal against a conduit, wherein the top packer segment is a component of the packer assembly. 
     
     
       3. The assembly of  claim 1 , wherein the ram comprises a non-circular cross-sectional shape. 
     
     
       4. The assembly of  claim 1 , comprising a bearing positioned between a flange of the threaded shaft and a support surface of a bonnet or a motor housing. 
     
     
       5. The assembly of  claim 1 , comprising:
 a second ram comprising a second threaded opening; 
 a second threaded shaft configured to engage the second threaded opening; and 
 a drive mechanism configured to enable the motor to drive rotation of the threaded shaft and the second threaded shaft. 
 
     
     
       6. The assembly of  claim 5 , wherein the drive mechanism comprises a chain drive comprising:
 a drive shaft configured to be driven to rotate by the motor; 
 a first sprocket gear coupled to the drive shaft; 
 a second sprocket gear coupled to the threaded shaft; 
 a first chain looped around the first sprocket gear and the second sprocket gear; 
 a third sprocket gear coupled to the drive shaft; 
 a fourth sprocket gear coupled to the second threaded shaft; and 
 a second chain looped around the third sprocket gear and the fourth sprocket gear. 
 
     
     
       7. The assembly of  claim 1 , wherein the motor comprises an electric motor. 
     
     
       8. A blowout preventer, comprising:
 a housing defining a central bore; 
 a first ram positioned within the housing and comprising a first threaded opening; 
 a first threaded shaft configured to engage and terminate within the first threaded opening; 
 a second ram positioned within the housing and comprising a second threaded opening; 
 a second threaded shaft configured to engage and terminate within the second threaded opening; and 
 at least one motor configured to drive rotation of the first threaded shaft and the second threaded shaft, wherein rotation of the first threaded shaft causes the first ram to move along the first threaded shaft and rotation of the second threaded shaft causes the second ram to move along the first threaded shaft, thereby adjusting the blowout preventer between an open position and a closed position. 
 
     
     
       9. The blowout preventer of  claim 8 , wherein the first ram and the second ram comprise pipe rams comprising respective packer assemblies configured to seal against a conduit extending through the central bore. 
     
     
       10. The blowout preventer of  claim 8 , wherein the first ram and the second ram each comprise a generally circular cross-sectional shape. 
     
     
       11. The blowout preventer of  claim 10 , wherein the first ram and the second ram each comprise a respective alignment slot configured to receive a respective protrusion extending from the housing. 
     
     
       12. The blowout preventer of  claim 8 , comprising a first bearing positioned between a first flange of the first threaded shaft and a first support surface and a second bearing positioned between a second flange of the second threaded shaft and a second support surface. 
     
     
       13. The blowout preventer of  claim 8 , wherein the at least one motor comprises a first motor configured to drive rotation of the first threaded shaft and a second motor configured to drive rotation of the second threaded shaft. 
     
     
       14. The blowout preventer of  claim 8 , wherein the at least one motor comprises one motor configured to drive rotation of the first threaded shaft and the second threaded shaft via a drive mechanism. 
     
     
       15. The blowout preventer of  claim 14 , wherein the drive mechanism comprises a chain drive or bezel gears. 
     
     
       16. A blowout preventer, comprising:
 a housing comprising a generally cylindrical cavity; 
 a ram comprising a generally circular cross-sectional shape, wherein the ram is positioned within the generally cylindrical cavity of the housing and the ram comprises a threaded opening; 
 an alignment interface between the generally cylindrical cavity of the housing and the ram, wherein the alignment interface comprises an alignment slot defined by the ram and a protrusion extending from the housing that engage one another to block rotation of the ram relative to the housing, 
 wherein the alignment interface is defined by a lower surface of the ram opposite a top packer segment that is configured to create a seal against the housing, and 
 wherein the alignment interface is provided at a location that does not interfere with the seal between the top packer segment and the housing; 
 a threaded shaft configured to engage the threaded opening; and 
 a motor configured to drive rotation of the threaded shaft, wherein rotation of the threaded shaft causes the ram to move axially along the threaded shaft. 
 
     
     
       17. The blowout preventer of  claim 16 , wherein the ram comprises a pipe ram and comprises a packer assembly configured to seal against a conduit, and wherein the top packer segment is a component of the packer assembly. 
     
     
       18. The blowout preventer of  claim 16 , comprising a bearing positioned between a flange of the threaded shaft and a support surface of a bonnet or a motor housing.